Metro Ethernet Network With Scaled Broadcast And Service Instance Domains

ABSTRACT

A method of operation for a provider edge device of a core network includes receiving a customer frame from an access network; the customer frame having a first Virtual Local Area Network (VLAN) tag of a first predetermined bit length. The first VLAN tag including a service instance identifier. The service instance identifier of the first VLAN tag is then mapped into a second VLAN tag of a second predetermined bit length greater than the first predetermined bit length. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.  37  CFR  1.72 (b).

RELATED APPLICATIONS

The present application is related to co-pending application serial nos.______ filed ______, entitled, “System And Method For DSL SubscriberIdentification Over Ethernet Network”; ______ filed _______, entitled,“A Comprehensive Model For VPLS”; and ______ filed ______, entitled,“Scalable System And Method For DSL Subscriber Traffic Over An EthernetNetwork”, which applications are assigned to the assignee of the presentapplication.

FIELD OF THE INVENTION

The present invention relates generally to digital computer networktechnology; more particularly, to methods and apparatus for providingmetro Ethernet services.

BACKGROUND OF THE INVENTION

Ethernet originated based on the idea of peers on a network sendingmessages in what was essentially a common wire or channel. Each peer hasa globally unique key, known as the Media Access Control (MAC) addressto ensure that all systems in an Ethernet have distinct addresses. Mostmodern Ethernet installations use Ethernet switches (also referred to as“bridges”) to implement an Ethernet “cloud” or “island” that providesconnectivity to the attached devices. The switch functions as anintelligent data traffic forwarder in which frames are sent to portswhere the destination device is attached. Examples of network switchesfor use in Ethernet network environments are found in U.S. Pat. Nos.6,850,542, 6,813,268 and 6,850,521.

The IEEE 802.1Q specification defines a standard for Virtual Local AreaNetwork (VLAN). Broadcast and multicast frames are constrained by VLANboundaries such that only devices whose ports are members of the sameVLAN see those frames. Since 802.1Q VLANS typically span many bridgesacross area common network, identification of VLANs is achieved byinserting a tag into the Ethernet frame. For example, according to theexisting standard, a 12-bit tag that uniquely identifies a VLAN may beinserted into an Ethernet frame. This VLAN tag may be used to specifythe broadcast domain and to identify the customer associated with aparticular VLAN. The customer identifier is commonly referred to as theservice instance domain since it identifies the service provided for aparticular customer. In a service provider (SP) metro Ethernet network,the broadcast domain constrains the scope of traffic among networkdevices such that data packets are not multicast to all devicesconnected to the network. A system and method for efficientlydistributing multicast messages within computer networks configured tohave one or more VLAN domains is disclosed in U.S. Pat. No. 6,839,348.

The concept of a broadcast and a service instance domains is illustratedin FIG. 1, which shows a SP Metro Ethernet network 10 that includes aplurality of interconnected switches. Three provider edge (PE) deviceslocated on the periphery of network 10 connect with two differentcustomers, respectively represented by customer edge (CE) deviceslabeled CE₁ and CE₂. The broadcast domain (i.e., CE₁) is shown by thebold, heavy line, which defines the particular switches and the path orspan through the switches for traffic sent among the various customersites. The service instance defines the particular customer associatedwith a given data packet, e.g., the customer of the CE₁ sites asdistinguished from the customer associated with devices CE₂. Note thatin the example of FIG. 1, both customers use the same broadcast domain.Traffic associated with a particular customer is uniquely identified bythe service instance tag identifier.

FIG. 2 shows two data packet formats commonly used for sending framesover a Metro Ethernet network. Data packet format 11 complies with theIEEE 802.1Q specification and includes a customer MAC address fieldfollowed by a 12-bit VLAN tag that is used to specify both the broadcastdomain and service instance. The customers data payload is shown beneaththe VLAN tag. (The uppermost portion of the data packet is alsofrequently referred to as the “outermost” portion, with the lowermostbeing synonymously referred to as the “innermost” portion.) The 12-bitVLAN tag field means that the IEEE 802.1Q standard can support acombined total of up to 4,094 broadcast domains and service instancedomains. For instance, the IEEE 802.1Q standard can support 4,094broadcast domains, each corresponding to a single service instancedomain or a single broadcast domain with 4,094 service instance domains.By way of further example, U.S. Pat. No. 6,430,621 teaches a method andapparatus that provides for grouping nodes in multiple VLANs usingport-based VLAN grouping using IEEE 802.1Q based frame tagging.

Data packet format 12 corresponds to the proposed IEEE 802.1adspecification that supports so-called “Q-in-Q” encapsulation, or tagstacking mechanism. According to this draft standard, each data packetincludes an upper (i.e., outer) 12-bit tag that designates one of up to4,094 broadcast domains (or VLANs), and a lower (i.e., inner) tag thatidentifies one of up to 4,094 service instances. The proposed IEEE802.1ad standard thus alleviates some of the capacity limitationsinherent in the IEEE 802.1Q standard by permitting each broadcast domain(each VLAN) to include up to 4,094 service instances. However, althoughthe 802.1ad draft standard is capable of satisfying many multipointapplications, it remains inadequate for point-to-point applicationswhere a single device can multiplex/de-multiplex tens of thousands orhundreds of thousands of service instances within a single broadcastdomain. Furthermore, the number of broadcast domains in Metro AreaNetwork (MAN)/WAN applications can easily exceed the 4K limit. Inaddition, there are certain applications that require the end-user MACaddresses and/or the end-users Frame Check Sum (FCS) to be tunneledthrough the MAN/WAN Ethernet network, a feature which is unsupported bythe 802.1ad proposal.

Nortel Networks Corporation has proposed an approach known as“MAC-in-MAC” that attempts to solve the drawbacks inherent in the priorart. The Nortel proposal, however, is based on a flat VLAN domain (i.e.,no VLAN tag stacking) and has a number of disadvantages. First, theMAC-in-MAC approach does not differentiate between broadcast domains andservice instance domains; therefore, if the number of service instancesis substantially larger than the required number of broadcast domains,the network nodes (i.e., switches, bridges, routers, etc.) will beburdened with supporting as many broadcast domains as there are serviceinstances. Since more hardware/software intensive resources are neededto support a broadcast domain than a service instance, bandwidth suffersand network costs increase. Additionally, the MAC-in-MAC approach lacksinter-operability with 802.1ad bridges; lacks a feasible implementationcapable of supporting millions of broadcast domains; and requires thatall bridges within the network have the MAC-in-MAC capability, not justthe edge bridges.

By way of further background, U.S. Pat. No. 6,789,121 discloses a methodof providing a Virtual Private Network (VPN) service through a sharednetwork infrastructure comprising interconnected PE devices having CEinterfaces. Some of the CE interfaces are allocated to a VPN supportinga plurality of VLANs and are arranged for exchanging traffic data unitswith respective CE devices, each traffic data unit including a VLANidentifier. A virtual connection (VC) in the shared networkinfrastructure is directly derived from a known VPN identifier and aVLAN identifier known or discovered by a PE device. U.S. Pat. No.6,484,209 teaches a system configured to forward multicast data basedupon a first set of correlation data, wherein a first set of correlationdata maps multicast group identifiers to ports that are members of thecorresponding multicast groups. The switch core includes a second set ofcorrelation data which maps multicast group identifiers to I/O cardsthat include member ports.

Thus, there is a need for alternative methods and apparatus that wouldaccommodate the ever expanding number of broadcast domains and serviceinstances of MAN/WAN Ethernet Networks while overcoming the shortcomingsof past approaches.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription that follows and from the accompanying drawings, whichhowever, should not be taken to limit the invention to the specificembodiments shown, but are for explanation and understanding only.

FIG. 1 is diagram of a service provider network used to interconnectplurality of customer sites.

FIG. 2 illustrates two different prior art data packet formats.

FIG. 3 shows one embodiment of the extended VLAN format of the presentinvention.

FIG. 4 illustrates the use of the extended VLAN mechanism as a serviceinstance identifier according to one embodiment of the presentinvention.

FIG. 5 illustrates the use of the extended VLAN mechanism as a serviceinstance identifier according to another embodiment of the presentinvention.

FIG. 6 illustrates the use of the extended VLAN mechanism as a serviceinstance identifier according to still another embodiment of the presentinvention.

FIG. 7 illustrates the use of the extended VLAN mechanism as both abroadcast domain identifier and a service instance identifier accordingto one embodiment of the present invention.

FIG. 8 illustrates the use of the extended VLAN mechanism as both abroadcast domain identifier and a service instance identifier accordingto another embodiment of the present invention.

FIG. 9 illustrates the use of the extended VLAN mechanism as both abroadcast domain identifier and a service instance identifier accordingto yet another embodiment of the present invention.

DETAILED DESCRIPTION

An extended VLAN (E-VLAN) mechanism that can differentiate betweenbroadcast domains and service instance domains, and expands the numberof broadcast domains and service instance domains in Ethernet MAN/WANapplications is described. In the following description specific detailsare set forth, such as device types, protocols, configurations, etc., inorder to provide a thorough understanding of the present invention.However, persons having ordinary skill in the networking arts willappreciate that these specific details may not be needed to practice thepresent invention.

A computer network is a geographically distributed collection ofinterconnected subnetworks for transporting data between nodes, such asintermediate nodes and end nodes. A local area network (LAN) is anexample of such a subnetwork; a plurality of LANs may be furtherinterconnected by an intermediate network node, such as a router orswitch, to extend the effective “size” of the computer network andincrease the number of communicating nodes. Examples of the end nodesmay include servers and personal computers. The nodes typicallycommunicate by exchanging discrete frames or packets of data accordingto predefined protocols. In this context, a protocol consists of a setof rules defining how the nodes interact with each other.

Each node typically comprises a number of basic subsystems including aprocessor, a main memory and an input/output (I/O) subsystem. Data istransferred between the main memory (“system memory”) and processorsubsystem over a memory bus, and between the processor and I/Osubsystems over a system bus. Examples of the system bus may include theconventional lightning data transport (or hyper transport) bus and theconventional peripheral component [computer] interconnect (PCI) bus. Theprocessor subsystem may comprise a single-chip processor and systemcontroller device that incorporates a set of functions including asystem memory controller, support for one or more system buses anddirect memory access (DMA) engines. In general, the single-chip deviceis designed for general-purpose use and is not heavily optimized fornetworking applications.

In a typical networking application, packets are received from a framer,such as an Ethernet media access control (MAC) controller, of the I/Osubsystem attached to the system bus. A DMA engine in the MAC controlleris provided a list of addresses (e.g., in the form of a descriptor ringin a system memory) for buffers it may access in the system memory. Aseach packet is received at the MAC controller, the DMA engine obtainsownership of (“masters”) the system bus to access a next descriptor ringto obtain a next buffer address in the system memory at which it may,e.g., store (“write”) data contained in the packet. The DMA engine mayneed to issue many write operations over the system bus to transfer allof the packet data.

FIG. 3 shows the E-VLAN tag format in accordance with one embodiment ofthe present invention. An Ethertype associated with the E-VLAN may beused to identify this extended tag in an Ethernet frame. A key featureof the E-VLAN tag format is a 20-bit VLAN ID/Service ID field thatallows identification, in certain applications, of up to one milliondifferent service instances. Also included is a 4-bit Class of Service(CoS) field, a Discard eligible (D) bit, a FCS (F) bit, a customer MACaddress encapsulation (M) bit, and a stack (S) bit that indicates thatVLAN stacking is utilized in the data packet format. Setting of the Mbit indicates the entire customer frame, including the customer's MACaddress, is encapsulated in the Ethernet frame. In cases where the M bitis set, the provider MAC address is used for tunneling through the SPnetwork. These latter two features will be discussed in more detailbelow.

As will become apparent shortly, the E-VLAN tag mechanism can be used inmany different applications. For instance, when the E-VLAN tag isutilized as a service instance identifier, the E-VLAN tag may beembedded within an IEEE 802.1ad frame, replacing the inner tag normallyassociated with an 802.1ad frame. In such applications, there can be4,094 broadcast domains, with each broadcast domain supporting up to onemillion service instances. In applications where a given serviceinstance requires its own broadcast domain (i.e., one-to-onecorrespondence) a single E-VLAN tag may be utilized as both thebroadcast domain identifier and the service instance identifier. In suchapplications, the E-VLAN tag is the only tag in the Ethernet frame.

In still other cases, two E-VLAN tags may be utilized (i.e., one as thebroadcast domain and the other one as service instance domainidentifiers). In such applications, the E-VLAN tag is nested such thatthe outer tag represents the broadcast domain and the inner tagrepresents the service instance. Examples of these types of applicationsinclude situations where there are tens of thousands of broadcastdomains, where each broadcast domain has up to one million serviceinstances. Note that in applications where the E-VLAN tag is nested, asingle Ethertype may be used, and the S bit will be set to indicate tagstacking.

The extended E-VLAN tag of the present invention can also be used toindicate if the Ethernet frame contains end-user's FCS, for applicationswere FCS retention is required, as well as to identify when the Ethernetframe contains the end-user's MAC addresses, for applications where MACtunneling is required.

FIG. 4 illustrates use of the extended VLAN mechanism as a serviceinstance identifier across an Ethernet Service provider network inaccordance with one embodiment of the present invention. The serviceprovider network of FIG. 4 includes an Ethernet core network 20 that isshown connected to a pair of Ethernet access networks 21 & 22 vianetwork provider edge (n-PE) devices 32 & 33, respectively. User-facingprovider edge (u-PE) devices 31 & 34 connect respective customer edge(CE) devices 41 & 42 to Ethernet access networks 21 & 22. Data packetformat diagrams are shown under each corresponding network connectionextending between CE devices 41 and 42.

According to the embodiment of FIG. 4, a customer frame sent by CEdevice 41 arrives at u-PE device 31 with a data packet format consistentwith the IEEE 802.1Q specification, which format includes a customer MACheader, a customer VLAN tag, a Layer 2 protocol data unit (L2PDU)customer payload, and a customer FCS. In this example, access network 21is a Q-in-Q network such that, when the customer frame arrives, u-PEdevice 31 adds another 12-bit VLAN tag that identifies the serviceinstance and broadcast domain for connections across network 21. Whenthe data packet arrives at the edge of core network 20, n-PE device 32appends the data packet by taking the service instance identifierreceived from u-PE device 31 and mapping it to an E-VLAN (20-bit) tag. Aseparate VLAN tag may also be added on top of the E-VLAN at this pointto specify the broadcast domain spanning core network 20. (Practitionersin the networking arts will understand that the broadcast domain throughcore network 20 is separate and distinct from the broadcast domains ofaccess networks 21 and 22.)

Traffic traversing the right-hand side of the diagram of FIG. 4 (fromcore network 20 to CE device 42) follows the reverse process. That is,n-PE device 33 strips the VLAN (broadcast) and E-VLAN (service) tagsfrom the received data packets; mapping the 20-bit E-VLAN serviceinstance identifier to a 12-bit VLAN that specifies the broadcast domainand service instance domain for access network 22. Similarly, u-PEdevice 34 strips the VLAN (broadcast & service) from the Q-in-Q datapacket before forwarding to CE device 42.

It is appreciated that each of the u-PE and n-PE devices shown in theembodiment of FIG. 4 are configured to both append frames (adding theappropriate tags) headed in the direction from the CE device toward corenetwork 20, and to strip frames (removing the appropriate tags) headedin the direction from core network 20 to the CE device. In other words,the switches at the edge of the core and access networks are capable ofhandling both ingress and egress data traffic in the manner describedabove. By way of example, processing of the frames to add/drop tagfields may be performed by a software routine running on the centralprocessing unit (CPU) associated with the corresponding provider edgedevice.

Note that in the embodiment shown in FIG. 4, data packets in theEthernet core network 20 include a SP MAC header added by the n-PEdevice which encapsulates the customer MAC address. Encapsulation of MACaddresses in this manner is known as MAC tunneling, and provides amechanism for insuring that the customer's MAC addresses are not learned(i.e., they remain invisible) in all switches within core network 20.Practitioners in the networking arts will appreciate that the embodimentof FIG. 4 is useful in applications that rely upon devices in corenetwork 20 that are limited to operating on a 12-bit tag. The coreswitches will only see the upper tag, with the lower tag, i.e., theE-VLAN tag (service), being processed by n-PE devices only.

The embodiment of FIG. 5 is similar to that shown in FIG. 4, but withoutMAC tunneling in the core. Instead of an Ethernet core network, FIG. 5shows how the E-VLAN tag of the present invention may be used across aMulti-protocol label switching (MPLS)/Internet Protocol (IP) corenetwork 50. Because the core is MPLS/IP, the customer's MAC addressesare not visible in the SP core network. In this example, on the ingressside n-PE device 32 operates to map the service instance identifier ofthe 12-bit VLAN tag of access network 21 to a 20-bit E-VLAN tagidentifying the service instance for connections across core 50. On theegress side, n-PE device 33 maps the 20-bit E-VLAN tag back down to a12-bit VLAN that identifies both the broadcast domain and service domainfor access network 22. As can be seen, the core data packets alsoinclude an Ethernet over MPLS (EoMPLS) header for IP encapsulationacross core network 50.

Turning now to FIG. 6, use of the E-VLAN mechanism according to anotherembodiment of the present invention is shown. In this embodiment,encapsulation of the customer's MAC address and generation of the E-VLANtags occurs in access networks, i.e., at the u-PE device rather than atthe n-PE devices of core network 20. In other words, the E-VLAN tag isagain used as a 20-bit service instance identifier, but instead ofperforming the operations of adding and dropping the E-VLAN tags at n-PEdevices 32 & 33, those operations are performed by u-PE devices 31 & 34.In other words, in the example of FIG. 6, u-PE device 31 adds theservice instance E-VLAN and broadcast domain VLAN tags to each of thecustomer's frames prior to forwarding them across access network 21.Note that the customer frame is also encapsulated inside of the u-PE MACheader.

The E-VLAN tag remains unchanged through core network 20 and accessnetwork 22. However, it is appreciated that the VLAN tag designating thebroadcast domain in access network 21 differs from the broadcast domainVLAN tag in core network 20, which also differs from the VLANdesignating the broadcast domain in access network 22. That is, the onlything that n-PE devices 32 & 33 change in the data packets is the upperVLAN tag that defines the scope of the broadcast domain.

FIG. 7 illustrates the use of the extended VLAN mechanism as both abroadcast domain identifier and a service instance identifier accordingto another embodiment of the present invention. Whereas in the previousexamples, the E-VLAN tag is used to identify the service instance domain(i.e., the customer), in the example of FIG. 7, the E-VLAN tagdesignates both the broadcast domain and the service instance domainthrough Ethernet core network 20. The embodiment of FIG. 7 is thereforesimilar to that shown in FIG. 4, but without the additional VLAN(broadcast) added by n-PE device 32 in the core.

FIG. 8 illustrates the use of the extended VLAN mechanism as both abroadcast domain identifier and a service instance identifier with MACtunneling according to still another embodiment of the presentinvention. This embodiment is similar to that shown in FIG. 6, butinstead of stacked VLAN (broadcast) and E-VLAN (service) tags in theaccess networks 21 & 22, in FIG. 8 the broadcast domain and serviceinstance domain identifiers are both included in a single 20-bit E-VLANtag that is added by u-PE device 31 (for traffic flowing left-to-rightfrom CE device 41 to CE device 42) or u-PE device 34 (for trafficflowing right-to-left from CE device 42 to CE device 41).

The embodiment of FIG. 9 illustrates the use of the extended VLANmechanism as both a broadcast domain identifier and a service instanceidentifier with MAC tunneling according to yet another embodiment of thepresent invention. This embodiment is basically the same as that shownin FIG. 8, except that instead of a single E-VLAN tag for both thebroadcast domain and service instance identifiers, two stacked E-VLANtags are utilized. The upper E-VLAN designates the broadcast domain andthe lower E-VLAN identifies the service instance in the access domain.As before, the broadcast domain E-VLAN is changed by the n-PE device todefine the devices and path through core network 20, while the lowerE-VLAN (service) remains unchanged by n-PE devices 32 & 33.

It should also be understood that elements of the present invention mayalso be provided as a computer program product which may include amachine-readable medium having stored thereon instructions which may beused to program a computer (e.g., a processor or other electronicdevice) to perform a sequence of operations. Alternatively, theoperations may be performed by a combination of hardware and software.The machine-readable medium may include, but is not limited to, floppydiskettes, optical disks, CD-ROMs, and magneto-optical disks, ROMs,RAMs, EPROMs, EEPROMs, magnet or optical cards, propagation media orother type of media/machine-readable medium suitable for storingelectronic instructions. For example, elements of the present inventionmay be downloaded as a computer program product, wherein the program maybe transferred from a remote computer (e.g., a server) to a requestingcomputer (e.g., a customer or client) by way of data signals embodied ina carrier wave or other propagation medium via a communication link(e.g., a modem or network connection).

Additionally, although the present invention has been described inconjunction with specific embodiments, numerous modifications andalterations are well within the scope of the present invention.Accordingly, the specification and drawings are to be regarded in anillustrative rather than a restrictive sense.

1. A method of operation for a network-facing provider edge device(n-PE) of a core network, the method comprising: receiving a customerframe from an access network of a service provide (SP) associated with acore network, the customer frame having a first Virtual Local AreaNetwork (VLAN) tag of a first predetermined bit length, the first VLANtag including broadcast and service instance identifiers for connectionsacross the access network; mapping the service instance identifier ofthe first VLAN tag into a second VLAN tag of a second predetermined bitlength greater than the first predetermined bit length; andencapsulating the customer frame with a provide address header. 2.(canceled)
 3. The method of claim 1 further comprising: stacking a thirdVLAN tag on the second VLAN tag, the third VLAN tag being different fromthe second VLAN tag.
 4. The method of claim 1 wherein the core networkcomprises an Ethernet core network.
 5. The method of claim 1 whereincore network comprises a Multi-protocol label switching (MPLS)/InternetProtocol (IP) network.
 6. The method of claim 1 wherein the firstpredetermined bit length is 12-bits and the second predetermined bitlength is 20-bits. 7-11. (canceled)
 12. A method of operation for anetwork-facing provider edge device (n-PE) of a core network, the methodcomprising: receiving a customer frame from an access network of an SPassociated with a core network, the customer frame having a customerMedia Access Control (MAC) header, a customer Virtual Local Area Network(VLAN) tag and a first Virtual Local Area Network (VLAN) tag of a firstpredetermined bit length, the first VLAN tag including broadcast andservice a serviceinstance identifier identifiers for connections acrossthe access network; and mapping the service instance identifier of thefirst VLAN tag into a second VLAN tag of a second predetermined bitlength greater than the first predetermined bit length, the second VLANtag specifying a broadcast domain and a service instance domain of thecore network; and encapsulating the customer frame within a provideraddress header. 13.-14. (canceled)
 15. The method of claim 12 whereinthe core network comprises an Ethernet core network.
 16. The method ofclaim 12 wherein the access network comprises an Ethernet accessnetwork.
 17. The method of claim 12 wherein the first predetermined bitlength is 12-bits and the second predetermined bit length is 20-bits.18. A method of operation for a user-facing provider edge device (u-PE)of an access network, the method comprising: receiving a customer framefrom a customer edge (CE) device; adding a first Virtual Local AreaNetwork (VLAN) tag to the customer frame, the first VLAN tag designatinga broadcast domain in an access network; and adding a second VLAN taghaving a bit length of 20-bits or more to the customer frame, the secondVLAN tag designating a service instance identifiers identifier in theaccess network; and encapsulating the customer frame with a provideraddress header.
 19. (canceled)
 20. The method of claim 18 wherein theaccess network comprises an Ethernet access network.
 21. Anetwork-facing provider edge (n-PE) device comprising: a port to receivea customer frame from an access network associated with a serviceprovider (SP), the customer frame having a first Virtual Local AreaNetwork (VLAN) tag of a first predetermined bit length, the first VLANtag including a service instance identifier; and a processing unitconfigured to: map the service instance identifier of the first VLAN taginto a second VLAN tag of a second predetermined bit length greater thanthe first predetermined bit length; and encapsulate the customer framewith a provider address header, and also to stack a third VLAN tag onthe second VLAN tag, the third VLAN tag specifying a broadcast domainfor connections across a core network of the SP.
 22. (canceled)
 23. Then-PE device of claim 21 wherein the processing unit is furtherconfigured to stack a third VLAN tag on the second VLAN tag, the thirdVLAN tag being different from the second VLAN tag.
 24. The n-PE deviceof claim 21 wherein the first predetermined bit length is 12-bits andthe second predetermined bit length is 20-bits. 25-26. (canceled)
 27. Anetwork-facing provider edge device (n-PE) device comprising: a portconfigured to receive a customer frame from an access network, thecustomer frame having a customer Media Access Control (MAC) header, acustomer Virtual Local Area Network (VLAN) tag and a first VLAN tag of afirst predetermined bit length, the first VLAN tag including broadcastand service instance identifiers for connections across the accessnetwork; and a processing unit configured to: that maps map thebroadcast and service instance identifier identifiers of the first VLANtag into a second VLAN tag of a second predetermined bit length greaterthan the first predetermined bit length, the second VLAN tag designatinga broadcast domain and a service instance domain through a serviceprovider (SP) core network, and encapsulate the customer frame within aSP address header. 28-29. (canceled)
 30. The n-PE device of claim 27wherein the first predetermined bit length is 12-bits and the secondpredetermined bit length is 20-bits.
 31. A user-facing provider edgedevice (u-PE) device comprising: a port configured to receive a customerframe from a customer edge (CE) device, the customer frame including acustomer VLAN and a customer Media Access Control (MAC) header; and aprocessing unit configured to: add a Virtual Local Area Network (VLAN)tag having a bit length of 20-bits or more to the customer frame, theVLAN tag including broadcast domain and a service instance identifiersdesignating a broadcast domain and a service instance domain,respectively, for connections across the Ethernet access network andthrough a core network of a service provide (SP); and encapsulate thecustomer frame within a SP MAC header.
 32. (canceled)
 33. A provideredge device comprising: a plurality of ports; and means for adding afirst and second Extended Virtual Local Area Network (E-VLAN) tags to afirst frame received at a first port for transmission across a serviceprovider (SP) core network, the first frame including a customer MediaAccess Control (MAC) header and a customer VLAN tag, the first E-VLANtag designating a broadcast domain through an access network associatedwith the service provider (SP) core network, the first frame including acustomer Media Access Control (MAC) header and a customer VLAN tag, thefirst E-VLAN tag designating a broadcast domain through an accessnetwork associated with the service provider (SP) core network, and thesecond E-VLAN tag identifying a service instance through the accessnetwork and the service provide (SP) core network, the means also forencapsulating the first frame with a provider address header, the meansalso for dropping the first and second E-VLAN tags. 34.-36. (canceled)